I think it's best either to get a good variety of different types to try, which could be via a nappy library or second hand so it isn't too expensive, or to choose nappies that are very flexible and can be used in different ways to suit different shaped babies. I went for the latter and bought cotton terries and prefolds (Miosoft) with separate PUL wraps (Nature Babies worked better for us than the Miosoft ones and also fitted well with the terries) for day and lanolised knitted wool/alpaca covers for night. We also have hemp boosters and a few all-in-one nappies, Bumgenius Elementals, to wear with slimmer fitting clothes.
I made a list of criteria to help me choose my nappies and then picked what met them best. My reasons were:
Allergy friendly and biodegradable natural fibres also separate wraps and woollen covers minimise the amount of plastic used.
Flexible so likely to work well for any baby, allowing me to use the same nappies on subsequent children and ensuring they could be adapted to suit changes in shape or behaviour as the child grew.
Will be suitable from birth (lots of BtP nappies aren't) as I didn't want to use any disposables
Wool covers are cool and breathable so great on hot nights when you wouldn't want your baby's bum in a plastic bag! Also they allow the water in the urine to evaporate so they last longer without a change overnight.
Can be vigorously hot washed if needed after rotavirus vaccs and during stomach upsets
Fast drying and can be pan boiled (apart from PUL wraps and all-in- ones) if handwashing due to broken washing machine or away from home without access to a machine.
Available in plain white so doesn't show under baby clothes.